Podcast
Questions and Answers
What percentage of morphine is typically excreted unchanged in urine?
Which factor is NOT a contributor to the development of tolerance to opiates?
Tolerance to the effects of opiates develops at different rates for which reason?
In discriminative studies, morphine generalizes to which substances?
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When does withdrawal from opiates typically begin after the last dose?
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Which of the following is NOT a characteristic of opiates?
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Which substance is considered a semi-synthetic derivative of morphine?
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What type of receptors do opiates primarily act upon?
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Which of the following is a difference between synthetic opiates and natural opiates?
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Naloxone is an antagonist that can counteract the effects of opiates. What is its primary use?
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Which of the following is NOT considered an opiate?
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Which of these opiate effects is primarily linked to reinforcement in the brain?
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What main active component is extracted from the sap of opium poppies?
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What is the primary route of administration for codeine?
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Which drug is considered a semi-synthetic opiate derived from morphine?
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Which synthetic opioid is known for its use in cough mixtures and is sometimes abused in a practice called 'roboing'?
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Which historical figure is associated with the medical use of opiates around 460 BC?
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In what year did Dr. Alexander Wood discover the method of injecting morphine?
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What was the significance of the year 1898 in the history of opiates?
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Which route of administration is commonly associated with heroin?
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Which of the following opiates is known for being 10 times more lipid soluble than morphine?
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What is the main reason that morphine is less effective when taken orally compared to being injected?
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Which statement correctly describes heroin's ability to enter the brain?
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Which phase of metabolism do opiates primarily undergo in the liver?
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What is the primary active form of codeine in the body?
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Which of the following is true about the distribution of opiates in the body?
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In what form is heroin usually administered?
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What is a characteristic of the active ingredients of opiates?
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Which act banned morphine, opium, and cocaine in the US?
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Study Notes
What are Opiates?
- Opiates are opium-like substances and include:
- Morphine
- Codeine
- Heroin
- Synthetic opiates like meperidine, methadone, and dextromethorphan
- Endogenous opiates
Narcotics
- Opiates are also known as narcotic analgesics
- These substances reduce sensitivity to pain and increase sleep.
- Most opiates share:
- Sedative-hypnotic and analgesic properties
- Act on endorphin/enkephalin receptors
- Actions are antagonized by naloxone (Narcan)
Opium
- Opium is extracted from poppies.
- The active ingredients are found in the seedpod sap.
- The two main active ingredients are:
- Morphine
- Codeine
Heroin
- Heroin is derived from morphine.
- It is described as a "semi-synthetic" opiate.
- Heroin is ten times more lipid soluble than morphine, leading to faster absorption and higher concentrations.
Synthetic Opioids
- Synthetic opioids are chemically different from natural opiates but mimic their effects.
- These include:
- Meperidine (pethidine)
- Fentanyl
- Dextromethorphan (found in cough mixtures)
- LAAM
History of Opiates
- Opium cultivation dates back to 6000 BC in the West Mediterranean.
- By 1300 BC, use spread to Egypt.
- By 200 BC, opium use spread through the Middle East.
- Opium was introduced to China by Arab traders in 400 AD.
History of Opiates: 17th - 19th Century
- In 1680 Sydenham produced "Sydenham's Laudanum" - a mixture of:
- Opium
- Sherry wine
- Herbs
- In the 1700s, the Chinese began smoking opium instead of tobacco.
- By 1767, the import of opium to China reached 2000 chests per year.
- The British East India Company had a monopoly on the opium trade by 1793.
- British opium consumption increased between 1825-1875.
- Morphine was introduced as a prescription medicine.
- 1839-1841: First Opium War
- 1843: Dr. Alexander Wood discovers injecting morphine.
- 1856: Second Opium War
- 1874: Heroin was synthesized by C.R. Wright.
- 1890: The US imposes tax on opium and morphine.
- 1895: Dreser "invents" heroin.
- 1898: Heroin is marketed by Bayer pharmaceutical company.
- 1900s: St. James Society campaigns for free heroin for morphine addicts.
- 1905: The US Congress bans opium.
- 1910: The Chinese dismantle the India-China opium trade.
- 1914: Harrison Narcotic Act bans morphine, opium, and cocaine.
Administration, Distribution, and Excretion
- Morphine is a base with a pKa of 8.0.
- This makes it less effective when taken orally compared to injection.
- Oral administration results in:
- Significant "first pass metabolism" in the liver.
- Slow absorption, which can be desirable for analgesic purposes.
Ionization of Drug Molecules
- The degree of ionization of drug molecules depends on the acidity of the environment and the molecule's pKa value.
Administration, Distribution, and Excretion: Heroin
- Heroin is typically administered through injection.
- Other administration methods include:
- Intranasal (snuff)
- Inhaling (chasing the dragon)
Distribution
- Opiates concentrate in the:
- Heart
- Lungs
- Kidneys
- Liver
- Spleen
- Opiates bind to proteins in the blood.
- Opiates pass through the placenta more readily than the blood-brain barrier due to low lipid solubility.
- Heroin, however, is highly lipid soluble and enters the brain easily.
- Within the brain, opiates concentrate in the:
- Basal ganglia
- Amygdala
- Periaqueductal gray matter
Metabolism
- The primary active ingredients:
- Morphine
- Heroin's active metabolites are morphine and monoacetylmorphine
- Codeine's active metabolites include morphine, norcodeine, and codeine-6-glucoronide
- The liver handles the metabolism in two phases:
- Initial phase: digestive system enzymes (CP450)
- Second phase: metabolic interference using enzymes to conjugate the drug molecule with a water-loving substance
- These metabolites are then excreted by the kidneys.
Excretion of Morphine
- Active transport mechanisms remove morphine from the brain.
- 10% is excreted unchanged in urine.
- Morphine's half-life is 2-4.5 hours.
- 90% of codeine is eliminated.
Tolerance
- Rapid tolerance develops to most opiate effects.
- Tolerance develops (and disappears) at different rates for different effects.
- Tolerance is attributed to:
- Metabolism
- Receptor interactions
- Learning (context-dependent effects)
Cross Tolerance
- Cross-tolerance exists between different opiates.
- Cross-tolerance does NOT exist with depressants, stimulants, or hallucinogens.
- Partial cross-tolerance exists with alcohol.
Withdrawal
- Opiate withdrawal is not fatal.
- It begins 6-12 hours after the last dose.
- Withdrawal peaks in 1-3 days.
- Withdrawal usually subsides within a week.
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Description
Explore the world of opiates and narcotics through this quiz. Learn about their properties, classifications, and effects on the body. This quiz covers various opiates including morphine, codeine, heroin, and synthetic opioids, helping you understand these important substances.
